지구 귀환 시 좌측 날개로 과열 가스가 침투하는 문제가 있었던 것은 비단 우주선 컬럼비아호만이 아니었다. 지난 8일 NASA에서 배포한 보고서 내용이다.

3년전, 그러니까, 지난 2000년 우주 비행선 아틀란티스 호가 궤도에 진입할 때 이미 날개 선단(leading edge)에 ¼ 인치 크기의 균열이 있는 상태였고 대기권 재진입 시 엄청난 고열의 화염 플라스마가 비행선 날개의 안쪽으로 흘러들어가 거대 폭발의 시발이 될 수 있었던 것이다.

올 초 2월 1일 7명의 우수한 우주 비행사들의 목숨을 앗아간 컬럼비아 호 폭발의 경우와 달리, 아틀란티스 호는 날개 내부의 구조물만 파괴되는 수준의 작은 손상만 야기되어 천만 다행으로 비극은 빗겨갈 수 있었다고 보고서는 밝히고 있다.

AP 통신을 통해 미항공우주국에서 배포한 상기 문서는 소위 정보의 자유에 관한 협약, 즉 Freedom of Information Act (FIA)에 따라 공개된 것이다.

이에 따르면, 아틀란티스 호 날개 선단에 치명적 틈새가 생겼던 이유는 1997년으로 거슬러 올라가는 바, 당시 캘리포니아 주 팜데일(Palmdale)에서 보수/정비 중에 작업자들이 단열재를 날개 부위에 삽입시키면서 제대로 넣지 않고 부적절하게 끼워 맞춘 것이 사건의 발단이었다고 알리고 있다. 제대로 넣었으면 딱 들어맞게 놓여 있어야 할 단열재가 엉키고 섥혀 밖으로 다 드러난 채 날개 선단에 액체 등이 유입할 수 있는 공간(cavity)이 남게 된 것.

NASA 보고서의 발표에 관한 회신으로, 컬럼비아 호에 직접 관련되지 않은 사건 조사 관계자가 밝히길 아틀란티스 호 귀환 때 그런 문제가 이미 예견되었으면 NASA에서는 초강경 비상대책을 수립하여 문제의 근원을 완전히 해결했었어야 했다고. 우주 비행선 프로젝트에 오래 몸담아 온 전문가인 세인트 루이스 대학 항공우주 공학과 석좌 교수 폴 차이즈 교수의 지적이 이어진다. “충분히 위험한 경고를 이미 받아놓고 그냥 그것을 무시해버렸다고 실토하고 있습니다.”

When discussing the potential damage to the Columbia from the foam insulation that hit the leading edge panels of the wing some 80 seconds into the launching, Professor Czysz said, NASA officials "should have said, `If that opened up a crack any bigger than the one on Atlantis, we're in deep trouble.' "
He added, "Somebody ought to have his backside kicked so hard that it hurts."
But an astronaut on that May 2000 mission, Mary Ellen Weber, disagreed. "Absolutely, people knew if you have a breach in the wing, bad things can happen," Dr. Weber said. "That isn't news.
"Knowing what I know now about gas entering the shuttle's wing, do I believe the mission I was on was any more risky than I thought it was when I took off? No."
Dr. Weber, now an associate vice president at the University of Texas Southwestern Medical Center in Dallas, said she was not informed of the wing damage after the mission, though she said that NASA may have passed along the information to others in the astronaut corps.
But every astronaut knows the risks of space flight, she said. After the Columbia investigation, she said, "we may fix this particular problem — but I guarantee the next time astronauts get on that shuttle there will be a thousand other things that can happen."
"That is one of the risks we take in trying to become a spacefaring civilization," she went on. "I feel proud, and very fortunate, that I had the opportunity to take those risks."
As it happens, the Atlantis wing that sustained the quarter-inch breach was the same one that contributed a panel from its leading edge to a pivotal test in the investigation of the loss of the Columbia.
In that test, done on Monday at the Southwest Research Institute in San Antonio, a chunk of insulating foam was fired at the panel, opening a gaping hole of 16 by 16 inches. Members of the independent board investigating the Columbia accident say the test validated their theory that foam shed on liftoff damaged the wing in a way that led to the loss of the shuttle and its crew on re-entry.
In the Atlantis's 2000 mission, according to the NASA in-flight anomaly report, the much smaller gap caused a "substantial flow path" of plasma past the protective leading edge panels. The report found that "attaching hardware shows various signs of overheating," but that "the fittings do not exhibit any signs of melting or distortion."
A NASA spokesman, Allard Beutel, said the only damage discovered by NASA after the flight was to the piece of insulation itself. "The only component that needed to be replaced was the butterfly gap filler seal that was installed improperly in the first place," Mr. Beutel said.
The entire shuttle fleet was inspected for similar problems, and workers received new training in installing the part "to make sure that it never happened again," Mr. Beutel said.
John L. Crassidis, an associate professor of mechanical and aerospace engineering at the State University of New York at Buffalo, said the Atlantis crew was lucky that the hole in the wing was too small to cause serious damage. "Obviously, the size of the hole is important, too, and it's where it is," Professor Crassidis said.
Engineers work to eliminate places where a single point of failure can cause large-scale damage, like the O-rings that led to the loss of the shuttle Challenger in 1986. "Unfortunately," Professor Crassidis said, "nature finds a way of finding our Achilles' heel."
Outside Washington yesterday, members of the board investigating the Columbia breakup told members of Congress that their inquiry was proceeding well but that their report would not be ready until early August, according to participants in the meeting.
The board had been trying to deliver its report before Congress's August recess. The House is now scheduled to go home on July 24, and the Senate a week later. But participants said the members of Congress did not appear upset by the delay.
"The message we gave them, that we've given them before, is that the important thing is to get the report done in a way they feel totally comfortable with, and not to meet any particular deadline," said David J. Goldston, chief of staff of the House Science Committee.
The chairman of that committee, Representative Sherwood Boehlert, Republican of New York, and several other House members had lunch with 10 of the 13 members of the investigation board, at the board's offices in suburban Virginia.
The board does not appear to have been delayed by internal dissension or any technical issues, participants in the lunch said. One investigator said the board now had about 1,000 pages of draft material, which it was seeking to reduce to about 300 and to translate into lay language.
The document that the board is now trying to release at the beginning of August will be the first volume of its report; various appendices will follow in the next few weeks, people involved in the investigation said.
When the board was created, some officials said they hoped for a report within 60 days, but almost immediately it became obvious to participants that a thorough study was not possible in that period.
















Test Shows Foam Was Likely Cause of Shuttle's Loss
By MATTHEW L. WALD with JOHN SCHWARTZ


SAN ANTONIO, July 7 — A test intended to replicate the damage caused to the shuttle Columbia by foam debris during liftoff punched a gaping hole in a wing panel today, leading the investigator in charge of the experiment to declare, "We have found the smoking gun."
The test, at the Southwest Research Institute here, drew gasps from technicians, engineers and reporters gathered to see it. This was the second test using actual shuttle material; the previous one produced small cracks.
"I believe that we've established that the foam block that fell off the external tank was in fact the most probable cause, the direct cause of the Columbia accident," said the investigator, G. Scott Hubbard, a physicist who is a member of the Columbia Accident Investigation Board.
Mr. Hubbard said the hole — about 16 by 16 inches — was larger than expected but within the estimated range of the hole that experts believe led to the shuttle's destruction when it re-entered Earth's atmosphere the morning of Feb. 1.
In addition, Mr. Hubbard said, the mystery "Day 2 object" — observed by radar floating away from the orbiter in its second day of flight — may have been a chunk of the wing panel.
Today's test was the last major piece of research by the board, which is to announce soon when it will release its report, expected to be later this month. But the National Aeronautics and Space Administration plans to continue the work here, to develop a more thorough understanding of the performance of the panels on the wing's leading edge, made of a material called reinforced carbon-carbon that comprises carbon fibers in a matrix of carbon glue.
The results have several difficult implications for the space agency. The investigation board has already recommended that the shuttle carry a patch kit, for example, but whatever the possibility for patching a slit or a crack, a hole of about 256 square inches would appear to be much tougher to repair in space.
An agency spokesman, Allard Beutel, said it was unclear what effect the test would have on preparations for a return to flight for the shuttles. "We don't know how it's going to have an impact at this point," Mr. Beutel said, but he added that the test results were in line with the goals of the return-to-flight effort.
"The point is not to have debris hit any part of the shuttle; that's what we're working on," he said. "The whole point is to make the shuttle safer, so not having any debris hit the shuttle is our goal."
An outside expert said that the hole produced today was probably larger than the one on the Columbia, but added that the two tests conducted here were important because they set "the two extremes" of damage that the foam could have caused: a tiny crack or an enormous hole.
"It probably wasn't this large a hole," said the expert, Paul A. Czysz, a professor emeritus at Parks College of Engineering and Aviation at St. Louis University.
Otherwise, Professor Czysz said, the shuttle "would have probably broken up over California," instead of Texas, on its path to the Kennedy Space Center in Florida.
On the other hand, the spacecraft would probably have broken up east of Texas if the damage had been the small crack caused in the earlier test, Professor Czysz said.
In the test today, researchers shot a 1.67-pound chunk of foam, about the shape of a box of doughnuts, toward the wing at more than 500 miles an hour, using a gun that is ordinarily used for testing airplane windshields against bird strikes.
The intention was to hit one of the 22 wing panels in a way that would produce cracking or a small gap at the outboard edge. Mr. Hubbard said that the test conditions used average values for estimates of the speed and mass of the foam, and angle of impact. The target was a wing panel borrowed from the shuttle Atlantis, on which it had been through 27 flights. The Columbia's fatal flight was its 28th.
After a brief countdown and a bang from the gun, the next sound was gasps from a crowd of engineers, researchers and reporters. Mr. Hubbard threw his hands in the air in what seemed to be a mixture of surprise at the size of the hole and vindication that foam could inflict severe damage. On the basis of mathematical models and previous tests, he said, today's gaping hole was "completely unexpected."
The test results were severe enough to destroy a camera and some sensors embedded in the wing model. Technicians took turns climbing a ladder and sticking their heads inside the hole.

Associated Press
In the last major piece of research by shuttle investigators, foam was fired on Monday against a shuttle wing panel, producing a 16-by-16-inch hole.

The actual impact is impossible to duplicate with confidence. Among other variables, the foam chunk, which came from the shuttle's external fuel tank about 82 seconds after launching, was tumbling as it fell, and there is no way of knowing if it struck with one corner first, or with a whole edge first, as was done in this test. Also, Mr. Hubbard said that even when new, the panels vary in their resistance to breakage by 70 percent.
Investigators have given various figures for the size of the hole needed to produce the effects observed in the Columbia — heat readings in some sensors and failure in others, followed by loss of part of the left wing and destruction of the shuttle. They have talked about a hole from 6 to 10 inches square. Mr. Hubbard said today that because of the variability inherent in the testing, those holes, and the one produced today, were all "in the same ballpark."
The larger the hole, the greater chance that it could have been detected in orbit, had NASA asked for help from spy satellites, as some of its engineers urged during the flight.
But Mr. Hubbard noted that the lighting would have had to be right, because the broken surface was black, and the area inside was as well. Still, he said, it would easily have been visible to a spacewalking astronaut. The NASA administrator, Sean O'Keefe, had argued that fatal damage to the wing's leading edge might have been too small for an astronaut in a spacesuit to see.
During the Columbia's 16-day flight, engineers concluded that the foam could not have done enough damage to the brittle ceramic tiles on the underside of the shuttle to threaten the mission. But the space agency has very little data about how reinforced carbon-carbon, which is chosen not for strength but for its ability to withstand heat, would withstand impact.
Immediately after the breakup, Ron D. Dittemore, then the manager of the shuttle program, said he did not believe that foam could have been the cause.
But the independent board, saying it would take nothing for granted, concluded early that the shuttle was destroyed on entry by a breach on the left side that allowed in hot gases. Eventually the board localized the breach to a small section of the left wing. Then it set about to determine how tightly it could tie the foam strike, known to be in that region, to the breach.
Completion of the test was complicated. There are very few spare reinforced carbon-carbon panels, and each costs about $800,000 and takes months to fabricate. The hardware involved today, including supporting parts like those in a real wing, and cameras that shoot thousands of frames a second, cost $3.4 million, Mr. Hubbard said.
Today the foam hit within a quarter-inch of the area established as a target, at a speed of 777 feet a second, nearly equal to the 775 desired. It struck a glancing blow on the lower side of the curved leading edge of the wing, at about 22 degrees.
Asked if a hole the size of the one produced today would have been noticed on liftoff, Mr. Hubbard said probably not. It was just at the limit of detection for the video camera focused on the underside of the shuttle during liftoff, he said.

NASA Makes Big Changes in Shuttle Management
By JOHN SCHWARTZ and WARREN E. LEARY


NASA announced sweeping changes in the management of the shuttle program yesterday in a move that looks back to the loss of the shuttle Columbia on Feb. 1 and forward to the hard-hitting report on the disaster that is expected at the end of this month.
The moves bring a number of new people known largely for their engineering expertise to replace or supplement members of the management team that was in charge at the time of the fatal mission.
But the departure of only one member of the mission management team was officially announced yesterday: Ralph Roe, the orbiter project manager. In a move that surprised many inside and outside of NASA, Mr. Roe was named to head a newly created office to provide independent assessments of safety and engineering for all programs of the National Aeronautics and Space Administration.
In a telephone briefing with reporters last night, Bill Parsons, who succeeded Ron D. Dittemore in June as the shuttle program manager, said the new managers will "help me pull this program together and help me decide the direction this program needs to go in the future."
Mr. Parsons announced the shuttle program management changes to colleagues yesterday at an 8 a.m. meeting at the Johnson Space Center. An engineer who attended the meeting said the group expressed concern about some of the new appointees. Mr. Parsons apologized for the abrupt changes, the engineer recalled, and added that he said, "We have to get out in front of this and get on with it."
To many within the space agency, the moves represented an attempt to take action before the report on the investigation is released at the end of this month and show that the agency is taking charge of its problems. The agency administrator, Sean O'Keefe, warned workers in Houston last week that the report from the independent commission investigating the Columbia accident would be "really ugly" and sharply critical of the space agency's management. Mr. O'Keefe did not take part in yesterday's announcement.
In the briefing with reporters yesterday, Mr. Parsons said that accountability was an important part of his management style. "I'm a former marine, and I truly appreciate being held responsible and accountable," he said.
But when asked whether his use of the word "accountability" implied that people would be fired, he replied, "No, that's not what I meant," and added: "Should people be in fear? Absolutely not."
The changes within the shuttle program come in the midst of a broader management shakeup throughout the space agency. Arthur G. Stephenson, who had been director of the Marshall Space Flight Center, announced in May that he would step down. The center manages the external tank that shed insulating foam that struck the shuttle's wing some 80 seconds after liftoff.
Last month Mr. O'Keefe shifted Gen. Roy D. Bridges from his job as director of the Kennedy Space Center to run NASA's Langley Research Center, where engineers who were consulted during the flight had urged closer attention to the potential for grievous damage to Columbia from the foam strike.
The agency statement yesterday did not mention whether anyone would be leaving the shuttle program. The engineer who attended the meeting said that one of the NASA managers who will be removed from management is Lambert Austin, who had come under criticism for passing along a flawed analysis by Boeing engineers of the possible damage caused by the piece of insulating foam that struck the wing.
A member of Mr. Austin's family reached by telephone last night said he could not confirm whether Mr. Austin was leaving the shuttle program office.
Some people inside and outside the agency said they were surprised that Mr. Roe, a manager so closely associated with the team that has been criticized for giving short shrift to the safety concerns of engineers during the Columbia mission, would be put in charge of the new office for independent safety assessment for the program.
Early in the course of the investigation into the Columbia accident, Adm. Harold W. Gehman Jr., the head of the board, asked that the space agency remove Mr. Roe and another manager, Linda Ham, from management responsibility on NASA's side of the investigation in order to eliminate the potential for a conflict of interest that could result from managers investigating their own actions. After sending a heated letter of protest to Admiral Gehman, Mr. O'Keefe removed both Mr. Roe and Ms. Ham from a management role in the investigation, though they continued to work with the board in a lesser capacity.
In the telephone briefing with reporters, Mr. Parsons supported Mr. Roe's appointment, and said that he "brings an absolutely unique engineering knowledge to that team."
At yesterday's meeting, Mr. Parsons reportedly said that he did not know what role Ms. Ham would have in the reconfigured shuttle program.
Howard E. McCurdy, a historian who is an expert on management at the space agency, said that moving Mr. Roe into such a prominent post was "part of the old NASA culture." He noted that the rocket scientist Wernher von Braun allowed his engineers to make one mistake. "Von Braun figured that once you made the mistake you'd never make it again," Mr. McCurdy said.
The changes include the appointment of John F. Muratore as manager of the systems integration office; he had previously served as assistant to the director of engineering at the Johnson Space Center. N. Wayne Hale Jr. will become acting deputy manager of the shuttle program, coming from Kennedy Space Center, and Steve M. Poulos Jr., will become acting manager of the orbiter project office. Also, Edward J. Mango will be deputy manager of that office, coming over from the Kennedy Space Center.
John P. Shannon will be acting manager for flight operations and integration; he worked closely with the independent board investigating the Columbia accident.

(NY Times)